Fiserv said it has 2,234 credit union core customers. Of those, more than 1,000 have more than $50 million in assets. Symitar said it has 824 core credit unions total. Advantage: Fiserv. However, Symitar president Ted Bilke refused to surrender the leadership mantle.

“Symitar has always been a prevalent name in the credit union space, but in recent years has particularly seen the reward of delivering core platforms that truly are 'open,'” Bilke said. “In the last three fiscal years, we have had a phenomenal 28, 35 and most recently, 44 competitive core takeaways. In the fiscal year just ended, five of those were billion dollar credit unions; we've had two more credit unions with assets over $1 billion already sign in this fiscal year.”

In a statement, Fiserv said its client loss rate over the last year was less than 2% of its entire base. The company also offered that the vast majority of those competitive losses were smaller credit unions, with fewer than $250 million in assets, who converted to CUSOs for core processing, not Symitar.

Mark Sievewright, president of Credit Union Solutions at Fiserv, addressed Bilke's claim that in head-to-head competitions against Fiserv's DNA core, Symitar wins more than 55% of the time.

Sievewright strongly disagreed, saying in competition between DNA and Symitar, Fiserv wins the majority of the time, and has the data to back it up. However, he declined to make the numbers public, saying he didn't want to engage in a client counting game.

Fiserv added in a statement, “The success we're having with DNA in the market speaks for itself. We're not sure how (Symitar's) claims were calculated, but based on our analysis … DNA is the client's choice more often than not.”

Sievewright also said Fiserv is on track to exceed 2013's client retention numbers, and over the last 18 months, the firm has seen unprecedented numbers of clients extending their contract beyond the standard five-year term. Fifteen to 20% of resigns have extended to seven years, he said, and one credit union signed a 10-year deal. He also said DNA has gained more new clients than Open Solutions did in the four years prior to Fiserv's acquisition.

“For some competitors, their point of distinction is to spread a message of fear, uncertainty and dread,” Sievewright said, noting that Fiserv instead, lets its products speak for themselves.

Bilke also talked up Symitar's success, saying more than 200 clients have been with the core for at least 15 years, with many of them averaging 15% to 25% growth per year since conversion, with some growing even more.

“The combination of technology and consistent, reliable client service have fueled that retention as well as new growth,” he said.

Fiserv disputed claims – aired by Bilke, among others – that credit unions were rejecting Fiserv cores because they are closed; that is, not readily open to integration of third party services.

The company said not only does it allow clients to connect to third-party providers, several hundred of its 2,234 clients have established integration points to third-party financial services providers like Digital Insight, PSCU, Q2 and others.

“We agree with industry analysts like Aite Group who feel strongly that digital channels are becoming an extension of core, and our ability to offer an integrated ecosystem is a benefit of our scale and key reason why many clients choose Fiserv. Many credit unions prefer to work with a single provider for core, channel and payment solutions. It is our practice to support the choices that our clients make about the approach that is best for them,” Fiserv said in its statement.

Read more: Third party experts weigh in on Fiserv vs. Symitar …

One other point of contention: Who has more credit unions with $1 billion and greater in assets? By Fiserv's count it had 85. Symitar, which counted both live installations as well as those contracted and scheduled to go live, claimed 91.

“We can't speculate on another vendor's pipeline. Rather than counting and segmenting clients into categories, we remain focused on driving best-in-class results for our credit union clients of all sizes,” Fiserv said.

Callahan & Associates data challenged Symitar's claim of market share superiority, showing Fiserv maintains its lead in cores. Per Callahan, Fiserv has 2,241 core customers overall, 91 of them credit unions of a billion dollars or more.

However, Bilke countered that as Symitar works through its installation pipeline, it will lead the $1 billion and larger category.

“We see ourselves in the leadership position in cores with credit unions,” he said.

Third party experts have been quick to offer insights into what is occurring in the core system market, especially for larger credit unions.

Brad Smith, president of core consultant Abound Resources in Austin, Texas, attributed the apparent Symitar rise to lingering problems faced by its arch rival, Fiserv. That firm suffered significant embarrassment when it killed off development of its Acumen core, which had been billed as a new core for a new era, but was plagued by problems.

In January 2013, Fiserv bought for roughly $1 billion competitor Open Solutions and its innovative DNA core, largely to satisfy the large credit unions for which Acumen had been intended.

“Fiserv has been focused on the OSI acquisition/integration and cleaning up the Acumen mess and still doesn't seem to have a good go-to-market strategy for larger credit unions. As they've stumbled, Symitar has been building on its success and still has the momentum,” Smith said.

Atlanta-based consultant David Gibbard, formerly a SVP at Birmingham, Ala.-based technology CUSO EPL, said Symitar is ascending because “credit unions feel they have more control over other solutions when they are on Symitar.”

That, he explained, is because Fiserv's reputation is that it prefers to use its own, proprietary solutions for home banking, mobile banking, and the like to augment a core.

Symitar, on the other hand, portrays its core system as open; that is, easy to interface with add-ons. That difference, Gibbard said, is gaining favor with credit union executives.

Sam Kilmer, a senior director at research firm Cornerstone Advisors in Scottsdale, Ariz., said, “Symitar already grabbed the momentum before, and now with their solid client satisfaction, Symitar has just increasingly become the safe option.”

Scott Hodgins, another Cornerstone senior director, expressed a similar opinion, but noted that all is not gloomy for Fiserv.

“Smaller credit unions buy Symitar for the safe bet; big credit unions because of their integration openness and very strong retail functionality. DNA is being much better received and more widely included in system selections now after the Fiserv acquisition.”